The ultimate goal of this project is the development of a catheter that can inject drugs directly into the wall of the coronary artery to prevent restenosis after angioplasty. MEMS (microelectromechanical systems) technology will be used to prototype miniature hollow needles from silicon substrates. Microneedle arrays will be integrated with low profile catheter delivery systems for transport to and from the deployment site within arteries. Finite element modeling will be used to generate robust needle designs, which will be subsequently fabricated using deep reactive ion etching and wet anisotropic etching of silicon. Different microneedle geometries and array layouts will be fabricated and evaluated for mechanical strength and penetration characteristics into filleted rabbit lilac and porcine coronary arteries. Two low profile catheter delivery systems will be developed to transport the microneedle array to the coronary artery. One approach will rely on a low profile balloon to house the microneedle array inside molded pockets within the balloon. The other approach will investigate a novel suction catheter that would house the microneedle during transport. Once at the deployment site within the artery, suction would be applied via a syringe to pull the vascular wall towards the catheter and force the microneedles into the tissue. Fluid delivery will be demonstrated by injecting Evan's Blue dye into the arterial wall. Experiments and computer modeling will be conducted to optimize the microneedle geometry and array layout for penetration and fluid delivery. Results of this R21 project will establish the feasibility for further development of microneedles for local drug delivery catheters that could be used to investigate the efficacy and delivery characteristics of anti-restenosis therapy delivered directly into the vascular wall. [unreadable] [unreadable]